Abstract:
The first comprehensive use of wavelet methods to identify non-stationary time-
frequency relations between North Atlantic ocean-atmosphere teleconnection
patterns and groundwater levels is described. Long-term hydrogeological time
series from three boreholes within different aquifers across the UK are analysed
to identify statistically significant wavelet coherence between the North
Atlantic Oscillation, East Atlantic pattern, and the Scandinavia pattern and
monthly groundwater-level time series. Wavelet coherence measures the cross-
correlation of two time series as a function of frequency, and can be
interpreted as a correlation coefficient value. Results not only indicate that
there are common statistically significant periods of multiannual-to-decadal
wavelet coherence between the three teleconnection indices and groundwater
levels in each of the boreholes, but they also show that there are periods when
groundwater levels at individual boreholes show distinctly different patterns of
significant wavelet coherence with respect to the teleconnection indices. The
analyses presented demonstrate the value of wave- let methods in identifying the
synchronization of groundwater-level dynamics by non-stationary climate
variability on time scales that range from interannual to decadal
